This application relates generally to rotary machines, and more specifically to seal assemblies between components of a rotary machine. In rotary machines, such as steam turbines for example, it is customary to employ a seal assembly having a plurality of arcuate segments to form a seal between two stationary components and between a stationary component and a rotating component. Generally, the arcuate segments are disposed in an annular groove of one of the components. Each arcuate segment further has a sealing face in opposition to the other component. The sealing function is achieved by creating relatively tight clearances between the sealing face of the arcuate segments and the opposing component.
During the operation of the rotary machine, and more particularly during startup, shutdown or transient operations, components experience different thermal expansion rates, which in turn governs the spacing between the arcuate segments as the components expand and contract. The ability to minimize leakage between the arcuate segments allows for the formation of an effective seal between the components. Minimizing leakage between the arcuate segments also significantly improves rotary machine performance and efficiency.
Accordingly, there is a need to provide a seal assembly having enhanced sealing capabilities throughout all phases of the rotary machine operation.